| 摘要 |
PROBLEM TO BE SOLVED: To provide a relay drive circuit capable of holing a relay similarly to a relay drive circuit without a resistor for power-saving and of saving power even in the case that voltage of a drive power supply is reduced after turning on the relay.SOLUTION: A relay drive circuit comprises: a first switch 7 for energizing a relay coil 3 applied with a fluctuation voltage to actuate a relay contact 4; and a holding circuit 5, 8 having a series-connected resistor 5 and a second switch 8 for energizing the relay coil 3 to hold the actuated state of the relay contact point 4, and connected in parallel to the first switch 7. After the energization to the relay coil 3 and the actuation of the relay contact point 4, only the second switch 8 is turned on. The relay drive circuit further comprises: detection means 10 detecting a terminal voltage at a fluctuation voltage side of the relay coil 3; and determination means (9) determining whether or not the detected voltage value is lower than a predetermined voltage value. When it is determined that the detected voltage value is lower than the predetermined voltage value by the determination means (9), the first switch 7 is turned on. |
